One small problem

Question

Program Description
There is a group of mountain climbers. This program shows all possible combinations of mountain climbers if they are put into teams of 3. The user inputs the number of mountain climbers. Output uses letters to represent each mountain climber.
Example:
user input = 5
output : ABC ABD ABE ACD ACE ADE
problem : it Outputs this instead:
ABC ABD ABE ACE ADE AEE
I TRIED VARIABLE TRACING BUT COULDN'T FIGURE OUT HOW TO FIX THE PROBLEM. PLEASE POST YOUR IDEAS AND SUGGESTIONS
import javax.swing.JOptionPane;
import java.awt.*;
class COMBO2
     public static void main(String  args[])
          String[]a={"A","B","C","D","E","F","G","H","I","J","K","L","M","N","O","P","Q","R","S","T","U","V","W","X","Y","Z"};
          int count=1;
          int count2=2;
          String firstmate=a[0];
          String secondmate=a[1];
          String thirdmate=a[2];
          String inputtwo= JOptionPane.showInputDialog(null, "Enter number of Mountain Climbers");
         int input=Integer.parseInt(inputtwo);
        while (count<=input-1)     
                  if (thirdmate==a[input-1])
                          System.out.print(firstmate+secondmate+thirdmate);
                          System.out.print(" ");
                          secondmate=a[count+1];
                          count+=1;
                   else if (thirdmate!=a[input-1])
                        System.out.print(firstmate+secondmate+thirdmate);
                        System.out.print(" ");
                      thirdmate=a[count2+1];
                      count2+=1;
         System.exit(0);
}

Answer 1

this is the program with the 3 for loops
I didn't quite understand those hints. it is still not working properly
its even more jumbled now, and i can't variable trace with 3 loops so i'm gonna need some more ideas guys.
user input : 5
output: ABD BBD CBD DBD EBD
import javax.swing.JOptionPane;
import java.awt.*;
class COMBO2
     public static void main(String  args[])
          String[]a={"A","B","C","D","E","F","G","H","I","J","K","L","M","N","O","P","Q","R","S","T","U","V","W","X","Y","Z"};
          int count=1;
          int count2=2;
          String firstmate=a[0];
          String secondmate=a[1];
          String thirdmate=a[2];
          String inputtwo= JOptionPane.showInputDialog(null, "Enter number of Mountain Climbers");
         int input=Integer.parseInt(inputtwo);
          for (int i = 0; i < input;i++) {
  for (int j = 1; j<input-(input-2); j++) {
    for (int k = 3; k < input-(input-4);k++) {
      System.out.print( a[i] + a[j] + a[k] +" ");
         System.exit(0);
}